The present invention is directed to a process for the preparation of fluorinated products of the formula: EQU R.sub.F --CHR.sub.1 --CHR.sub.2 --y
in which:
(a) R.sub.F represents a straight or branched perfluorinated chain C.sub.n F.sub.2n+1, with n being a whole number between 1 and 20; PA1 (b) y is selected from a hydroxy group, carboxylic group, nitrile group, epoxide group, thiol group, thiocyanate group, carboxylic ester group, acyloxy group, amide group, thioether group, halogen atom, or a saturated hydrocarbon radical substituted by one or more of the aforesaid functional groups; and PA1 (c) R.sub.1 and R.sub.2, which can be identical or different, can either be y or a hydrogen atom, or an alkyl, cycloalkyl or aryl radical, or they can also together constitute a divalent radical and thus form a cyclic derivative. PA1 (a) R.sub.F represents a straight or branched perfluorinated chain C.sub.n F.sub.2n+1, with n being a whole number between 1 and 20; PA1 (b) y is a functional group or a hydrocarbon chain into which one or several functional groups have been substituted; and PA1 (c) R.sub.1 and R.sub.2, which can be identical or different, can either be y or a hydrogen atom, or an alkyl, cycloalkyl, phenyl or alkylphenyl radical, containing from 1 to 12 carbon atoms, or they can also together constitute a divalent radical and thus form a cyclic derivative containing from 3 to 8 carbon atoms in the cycle.
The present methods of preparation of such products all require at least two stages of reaction. Thus, the derivatives in which R.sub.1 and R.sub.2 are hydrogen, i.e. EQU R.sub.F --CH.sub.2 --CH.sub.2 --y
have been obtained by nucleophilic substitution reactions of the R.sub.F CH.sub.2 CH.sub.2 I compounds followed by the appropriate chemical conversions. The derivative R.sub.F --CH.sub.2 CH.sub.2 COOH has, for instance, been obtained by hydrolysis of the nitrile R.sub.F CH.sub.2 CH.sub.2 --CN having itself been obtained by the reaction of the iodide R.sub.F C.sub.2 H.sub.4 I with a metallic cyanide (French Pat. No. 1,560,544), with the R.sub.F C.sub.2 H.sub.4 I being prepared by the radical addition of the R.sub.F I onto ethylene.
This reaction described, for instance, in U.S. Pat. No. 3,145,222 and French Pat. No. 2,103,459, furnishes iodinated derivatives which can be converted, in particular by reduction with zinc or by hydrogenolysis, into products identical to those of the process of the fluorinated products described above; ##STR1##
According to French Addition Certificate No. 2,373,503, it is possible to cause perfluoroalkyl iodides to react with olefins in a dimethyl sulfoxide medium and in the presence of metal pairs. Example No. 2 of this Addition Certificate thus describes the reaction of C.sub.6 F.sub.13 I and of acrylonitrile, in a DMSO medium and in the presence of Zn/Cu pair, which furnished C.sub.6 F.sub.13 C.sub.2 H.sub.4 CN with a yield of 50%. However, this reaction does not furnish reproducible results and the yields remain low.